...buut they seem to be in a different place in each individual Z3. On my July, 99 build date 2.3, the siren plug wires were taped to another set of cables near the rear of the driver's side of the engine compartment. I had to reach down around the fuse box and fumble blindly for the better part of 10 minutes before I found it. Several time I wished that my arm came with two wrist joints. My car is safely at home out of the rain that seems to finally be coming to the Bay Area, so I can't check, but I'm pretty sure it was between the fuse box and some sort of fluid reservoir. I want to say it was the brake fluid reservoir but it might be the power steering fluid (whatever, it's the small reservoir just forward of the box). The plug in question was taped to some wires almost directly between these.

You do not need to feed wires through to the passenger compartment. Good luck!

Mike

: But where do you plug it in? is it near the drivers side? do I have to fish wires into the car then conect to the alarm.

: : :You cannot buy the harness for the siren. Believe me, I tried. I even have the part numbers, but they are not available.

: : However, you can fashion your own harness using the black plastic cover from the harness and Radio Shack pins. : : The part number for the pins is 274-224 4ckt Male Molex. It's four pins with a plastic clip. The pins are all attached and have to be broken off. As they come, they are a loose fit into the siren harness. What I did was to tap a small nail into the back to widen the diameter. Then the fit was perfect and tight. This pin will also fit into the female trunk trigger wire adapter.

: : I took the black plastic cover from the car harness and drilled two holes in it. I inserted the wires and soldered them onto the pins. Then I just plugged the whole thing into the female harness, snapped on the cap and and taped it up.

: : For mounting the siren, there is a perfect place under the airbox(except for M). First, remove the airbox. There is one nut to loosen and two clips to undo. There is a small rubber hose clipped to the top of the box. Pull it off and you can remove the airbox assembly without any interference.

: : The airbox sits on a little rubber bumper, like a mushroom. Moving forward and towards the left front along the chassis right before you get to the headlight, you will see a ~3/8 inch in hole in the chassis. There is enough room behind to insert a bolt. Get a bolt that fits the hole and a nut and lockwasher. Remove the bracket from the siren. It's triangular. Drill out the top right hole in the bracket to fit the bolt(holding the point down and the curved part up and the siren mount up). Bolt the bracket using the hole in the chassis so that the point of the triangle faces forward and down. Loosely fit the siren on and position so that it faces forward and down. You will see that it clears the airbox and alternater pulley with no problem. Remove the siren, bolt down the bracket tight and mount the siren. Replace airbox.

: : Before you finally mount the siren, measure the wire length to the plug, cut wires, put on split loom or spiral wrapping, insert wires in drilled out plastic cap and solder on pins. Now, mount siren, route wires, tie down wires and plug in. You are done!